Magnetic drum assembly

ABSTRACT

A compact, lightweight magnetic drum assembly driven by synchronous motor means. The motor and drum assembly are respectively supported by separate mounting plates. A shaft for rotatably mounting the drum assembly is supported in a recess provided in the drum assembly mounting plate. The drum assembly is rotatably mounted upon the shaft. The rotor assembly is directly mounted upon and secured to the drum assembly so that the two components effectively form one rotating assembly. One of the mounting plates adjustably receives a magnetic head assembly, the adjustability allowing proper alignment of the magnetic heads relative to the magnetic surface of the drum as well as providing the proper air gap therebetween.

United States Patent [72] Inventor Richard B. Hanbicki 2,915,358 12/1959Richards 346/74 MD Princeton Junction, N.J. 3,119,102 1/1964 BraenB4G/174.1 F [21] Appl. No. 829,850 3,174,152 3/1965 Maclay. 346/74 MD[22] Filed May 15, 1969 3,390,385 6/1968 Ehalt 346/138 [45] PatentedNov. 2, 1971 Primary Examiner-Terrell W. Fears [73] Assigneelglillglporatm Assistant Examiner-Howard W. Britton Continuation-impartof application Ser. No. Anomeynostrolenk Faber' Gerb & soe 731,421, May23, 1968, now abandoned.

[54] MAGNETIC DRUM ASSEMBLY ABSTRAT: A compact, lightweight magneticdrum as- 10 Claims 15 Drawing Figs sembly driven by synchronous motormeans. The motor and drum assembly are respectively supported byseparate mount- [52] U.S. Cl 346/74 MD, lng plates- A Shaft folrotatablymounting the drum assembly ls 340/1 74-1 F 346/138 supported in a recessprovided in the drum assembly mounting [5I] Int. Cl G0ld15/'l 2, platoThe drum assmnbly ls rotatably mounted upon the shaft G1 lb 5/4861 1b5/76 The rotor assembly is directly mounted upon and secured to [50]Field ofSearch 346/74 M, the drum assembly so that the two componentseffectively 74 MD 138; 340/174-1 F form one rotating assembly. One ofthe mounting plates adjustably receives a magnetic head assembly, theadjustability [56] References Cited allowing proper alignment of themagnetic heads relative to UNITED STATES PATENTS the magnetic surface ofthe drum as well as providing the 2,905,933 9/1959 Canepa B4G/174.1 Fproper air gap therebetween.

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K /e 27d PAH-immuun 19H 3.618 120 SHEET l UF 4 PATENTEB Nnvz mx SHEET uUF 4 MAGNETIC DRUM ASSEMBLY This application is a continuation-in-partof application Ser. No. 731,421, filed May 23, 1968, now abandoned.

yThe present invention relates to magnetic storage means, and moreparticularly to a novel magnetic drum assembly which is of lightweight,compact size and of the utmost simplicity of design.

There exist a variety of applications wherein storage means must beprovided for any one of a variety of purposes. One typical example is acharacter display assembly, as set forth in detail in copendingapplication Ser. No. 718,553, filed Apr. 3, 1968, by the instantinventor and assigned to the assignee of the present application. Oneobjective of the character display system described therein is toachieve optimum compactness in arrangement and overall dimensions toallow adaptability of the display system within any type of systemrequiring a visual display capability. The character display systemdescribed in the above-mentioned copending application employs a memorymeans for storage of character and/or symbol information signals. Thememory system to be described hereinbelow lends itself admirably to usein the character display system of the above-mentioned copendingapplication in that it is compact in size, light in weight and has asimplicity of design to assure its reliability in operation and ease indisassembly for inspection and/or maintenance activities.

The magnetic memory means of the present invention is comprised of asynchronous motor designed to drive the memory drum at a predeterminedsubstantially constant angular velocity. The motor is mounted upon onemember comprising a mounting assembly.

The synchronous motor drives a rotor assembly mounted upon and rotatablewith a shaft joumaled within at least one bearing assembly, which issecured to said one member. The magnetic drum is comprised of asubstantially cylindricalshaped member open at one end and beingprovided with an annular-shaped surface which is press-fitted with acooperating flange provided on the rotor assembly, thereby securelymounting the rotor upon the cylindrical member for direct rotationtherewith. No mechanical engagement is required between the motor andthe rotor-drum assembly. The cylindrically shaped member surrounds therotor assembly and is positioned in close proximity to the synchronousmotor so as to greatly minimize the overall width of the assemblymeasured along the longitudinal axes of the cylindrical member, shaftand synchronous motor, all of which axes are coincident with oneanother.

The mounting assembly movably receives a magnetic head assembly. Theadjustability feature facilitates alignment of the magnetic headsrelative to the drum surface as well as facilitating adjustment forproviding the desired airgap between the magnetic heads and the drumsurface.

It is, therefore, one object of the present invention to provide a novelmagnetic drum memory assembly which is light in weight, compact indesign and of the utmost simplicity.

Another object of the present invention is to provide a novel magneticmemory storage means comprised of a synchronous motor, a rotor assembly,and a cylindrical-shaped magnetic drum member directly mounted to therotor assembly so as to completely surround the rotor assembly and Ie inclose proximity to the synchronous motor to provide a very compactarrangement.

Yet another object of the present invention is to provide a novelmagnetic memory storage means comprised of a synchronous motor, a rotorassembly, and a cylindricalshaped magnetic drum member directly mountedto the rotor assembly so as to completely surround the rotor assemblyand lie in close proximity to the synchronous motor to provide a verycompact arrangement and wherein the assembly is mounted upon a two-piecehousing provided with means for adjustably mounting a magnetic headassembly thereto, facilitating alignment between the drum surface andthe magnetic heads, and further facilitating the provision of a properairgap therebetween.

These as well as other objects of the present invention will becomeapparent when reading the accompanying description and drawings inwhich:

FIG. 1 is a perspective view showing the fully assembled housing.

FIG. 2a is a view of the housing assembly of FIG. l looking inthedirection 2-2'.

FIG. 2b is an elevational view of the housing assembly of FIG. l inwhich a portion thereof is broken away to expose the head assembly.

FIG. 2c is a view of the housing assembly of FIG. l looking in thedirection shown by arrows 2'-2' and with the housing cover plateremoved.

FIG. 3 is a sectional view of the assembly taken along the lines 3-3 ofFIG. 2b.

FIG. 4 is a perspective view showing the magnetic head retainer clipalso shown in FIG. 2a, 2b and 3.

FIG. 5a is a top view, partially sectionalized, of another preferredembodiment ofthe present invention.

FIGS. 5b and 5c are side and end views, respectively, of the embodimentof FIG. 5a.

FIG. 5d is a sectional view taken along the lines A-A of FIG. 5b.

FIG. 6a shows a plan view of a housing for mounting the drum-rotorassembly and magnetic head assembly comprising still another preferredembodiment of the present invention.

FIG. 6b is a sectional view of FIG. 6a looking in the direction ofarrows A-A.

FIG. 6c is a sectional view of FIG. direction of arrows B-B.

FIG. 6d is an end view of the embodiment shown in FIGS. 6ta-6c.

FIG. 7 is a plan view of a housing portion employed with the assemblyportion of FIG. 6a.

Refcning now to FIGS. l, 2a-2c, 3 and 4, there is shown therein amagnetic drum assembly l0 comprised of a housing 1l and housing coverplate l2. Housing Il has a substantially U-shaped configuration formedby a central portion lla integrally joined with substantially spacedparallel sides 1lb and llc (note especially FIG. 3). The central portionlla and sides 1lb and llc` are each provided with a pair of marginaledges 13a through 13e, respectively, which are bent or otherwise formedso as to provide curved portions defining grooves for slidably receivingthe cooperating edges of cover plate l2 which likewise has asubstantially U-shaped configuration which is defined by a centralportion or top cover plate portion 12a integrally formed with sides 12band I2C, respectively. The upper and lower edges of sides 12b and l2careslidably received between the grooves formed by edges 13b-13e. Theforwardmost edges of sides 12b and 12C are received within the groovesdefined by curve portions l3a,l3a so that when the cover plate 12 is inthe fully assembled position, as shown in FIG. l, the housing assemblysubstantially conceals and seals the components arranged within theinterior of the housmg.

A synchronous motor 14, positioned within the housing assembly, issecured to side llc in the manner best shown in FIGS. 2c and 3 byproviding suitable fastening members 15,15 passing through suitableopenings in side llc and spacers 16,16 which fasteners threadedly engagesuitable openings provided in the flanged portion.l4a,14a of the motorassembly. A centrally located opening 17 is provided within motor 14 forreceiving a bearing assembly 18 in which a first tapered end 19a ofshaft 19 is mounted. The synchronous motor is further provided with aplurality of arcuate-shaped projections l4b arranged at spaced intervalsaround an imaginary circle whose center lies on the longitudinal axis24. The projections are pole pieces which generate the desiredelectromagnetic field for rotation of the rotor assembly 26. Theprojections may be of differing arcuate length and have differingspacings therebetween to produce the desired revolving field. The polepieces may be of different lengths and spacings. The opposite taperedend l9b of shaft 19 is joumaled within a 6a looking in the bearingassembly which, in turn, is press-tted within a recess 22 provided intriangular-shaped bearing mount 2l, as best shown in FIGS. 2b and 3. Thebearing mount 21 is formed from a substantially flat, triangular-shapedplate which is bent or otherwise formed to provide a substantiallycircular-shaped recess 22 having a small opening 23 whose center lies onthe longitudinal axis 24 for shaft 19. The comers 21a-21e of the bearingmount are bent to extend toward the interior surface of side 1lb whichis provided with three openings 25a-25C for respectively receiving thebent ends 21a-21e` of lthe bearing mount. The tapers of each of the bentends act to center the bearing mount relative to the associated openingsin face plate l lb.

The rotor assembly 26 for motor 14 is comprised of a central portion 26a(which may be formed of aluminum) having an opening 26b so as to bepress-fitted to shift 19. The central portion 26a is secured to an outerring portion 26C having an outwardly bent cylindrical-shaped flange 26d.The revolving magnetic eld developed by motor 14 reacts with the outerportion 26e` (formed of a suitable ferromagnetic material) causingrotation (at a constant predetermined speed) of rotor assembly 26 whichis free to so rotate together with the freewheeling shaft 19.

A magnetic drum assembly 27 is comprised of a central portion 27a havinga central opening 27b whose center is coincident with the longitudinalaxis 24 of shaft 19. An annularshaped groove or depression 27e` isprovided in central portion 27a and is designed so that its surface,which lies furtherest away from the longitudinal axis 24 on the convexside of the depression, makes a firm press-fitting with the interiorsurface of cylindrical-shaped flange 26d provided in rotor assembly 26.The central opening 27b may also be designed to be pressfitted uponshaft 19. It should be noted that the drum assembly 27 completelysurrounds the rotor assembly 26 and further surrounds a portion ofsynchronous motor 14, thereby greatly reducing the width of the assemblymeasured along the longitudinal axis 24.

The central portion 27a of the magnetic drum assembly is integrallyformed with a cylindrical portion 27d whose exterior surface may becoated in any conventional fashion with a magnetic material capable ofbeing driven by a suitable magnetic recording head into either one oftwo opposite saturation states. One suitable material which may beemployed is a modified gamma iron oxide referred to as MO-9858 and isavailable from the Charles Pfeizer Company of Easton, Pennsylvania.

Energization of motor 14 generates a revolving magnetic field, causingrotation of rotor assembly 26 due to the magnetic coupling therebetweenwhich, in turn, causes rotation of shaft 19 and magnetic drum assembly27. The bearing assemblies 18 and 20 provide for freewheeling mountingof the shaft 19 and further acts to prevent any wobbling or eccentricityin the rotation of elements 26, 19 and 27.

Surface portion lla of housing ll is provided with a pair of narrow,elongated slots 28a and 28b and a slot 28e located between slots 28a and28b. A retaining clip 29 (note especially FIG. 2a) is employed forpositioning and securing a magnetic head assembly 35 to housing ll,which clip is comprised of a central portion 30 having integrallyformed, downwardly and inwardly depending legs 31 and 32 whose distalends 31a and 32a, respectively, are bent inwardly in themanner bestshown in FIGS. 2b and 4. Central portion 30 is provided with arectangular-shaped opening 33.

The magnetic head assembly is mounted to housing 1l in the followingmanner:

Sides 31 and 32 of retainer clip 29 are inserted into the two elongatedslots 28a and 28b, respectively. The magnetic head assembly 35 may bepositioned against the interior surface of housing side lla so that itsconnecting terminals 36 are free to pass through the slot 28C in surface11a. The retainer clip 29 which is formed of a suitable resilientmaterial is then pressed downwardly in the direction shown by arrows37-37 until the inwardly bent portions 31a and 32a embrace thediagonally aligned surfaces 35a and 35h of the magnetic head assembly inthe manner shown best in FIG. 2b. The central portion 30 of retainerclip 29 is curved, causing the embracing flanges 31a and 32a to firmlysecure the magnetic head assembly 35 in position.

It should be noted that the elongated slots 28a and 28b provide morethan sufficient clearance for passage of the sides 3l and 32 of retainerclip 29 therethrough. The magnetic heads 38 can be seen to be positionedto the right of vertical phantom line 39 which coincides with thediameter of magnetic drum assembly 27 and passes through its axis ofrotation 24. The clearance of elongated slots 28a and 28b and likewisethe clearance of slot 28C allows the magnetic head assembly 35, togetherwith retainer clip 29, to be moved in either of the opposing directionsshown by arrows 39 and 40 in order to adjust the gap between magneticheads 30 and the magnetically treated surface 27d of magnetic drumassembly 27. The resiliency of retainer clip 29 serves to maintain thealignment of the magnetic head assembly 35 once it is accuratelypositioned.

It should be noted that if the magnetic drum assembly requiresdisassembly for inspection, maintenance or other purposes, the removalof the cover plate assembly l2 from the main housing 11 does not in anyway affect the relative positioning between the magnetic head assembly35 and the magnetic drum assembly 27. Removal of the cover plate l2provides access to interior components along three sides to facilitateinspection and/or maintenance ofthe magnetic drum assembly.

The mounting of the magnetic drum assembly 27 directly upon the rotorassembly 26 so that the elements 26 and 27 may be considered as oneentity, greatly diminishes the overall size of the magnetic drumassembly, eliminates the need for an output shaft coupling the motor tothe magnetic drum and further reduces overall size and weight of theassembly. Magnetic drum assemblies of the type described herein whichhave been produced to date have housing outer dimensions of 2% inches by2.3 inches by 1.25 inches. As many as seven separate tracks have alreadybeen provided on such drum surfaces and additional tracks may beprovided by further judicious arrangement of the magnetic head assembly.The dimen sions set forth above are merely exemplary, and it should benoted that further reductions in size are possible, depending only uponthe needs of the user.

FIGS. 5a through 5d show another preferred embodiment of the presentinvention. Memory system 50, shown in this figure, is comprised of afirst mounting plate 5l having a plurality of apertures 52 (preferablyfour in number) for securing a second mounting plate 53 in spaced,parallel fashion thereto. The spaced, parallel alignment of the mountingplates 5l and 52 is achieved by means of a plurality of spacers 54(shown best in FIG. 5c), each of which is provided with a pair of tappedapertures 54a and 54b. The openings S2 in mounting plate 5l receive athreaded fastener 55 for threadedly engaging the tapped opening 54a ofan associated spacer 54. Mounting plate 53 is provided with suitableopenings 56 (preferably four in number), each receiving a threadedfastener which threadedly engages the tapped opening 54b of anassociated spacer 54. If desired, lockwashers 58 may be provided tomaintain the rigid fastening between fasteners 57 and spacers 54.

Mounting plate 5l is further provided with a centrally located opening59 for receiving a shaft 60 presstitted into the baseplate and therebyprevented from experiencing any rotational movement. A firstthrust-washer 6I is mounted upon shaft 60 and is positioned immediatelyadjacent the lefthand face of baseplate 51 (relative to FIG. 5d). Acylindricalshaped drum member 62 provided with a pair of sapphirebearings 63 and 64 secured within suitable cavities provided in thecylinder, is mounted upon shaft 60. The centrally located opening 65 ofcylinder 62 has an internal diameter which is slightly greater than theouter diameter of shaft 60. A second thrust-washer 66 is positioned uponshaft 60 adjacent the lefthand face of drum 62 relative to FIG. 5d. Aninterference fit retainer 67 is mounted near the le-hand end of shaft 60relative to FIG. 5d and provides a slight clearance between thethrust-washer 66 and the sapphire bearing 64 so as to limit the linearmovement of drum 62 relative to shaft 60 to a very slight amount whileallowing freewheeling rotation of drum 62 upon shaft 60. The sapphirebearings are preferably forcefitted into the cavities provided in drum62, and thereby act to seal the hollow interior between the outerperiphery of shaft 60 and the inner periphery of opening 65. Two orthree microdrops of oil placed within this hollow interior region remaincaptured within the interior space which acts as an oil reservoir forlubrication purposes. The oil captured in this manner will remaintherein for the life of the unit.

Drum 62 is provided with a circular-shaped outer periphery 68 having amagnetic coating 69 of substantially uniform thickness depositedthereon. The drums are preferably produced by coating the cylindersurface with a magnetic material. The coating 69 is sheared and trued tobe perfectly concentric. The shearing operation is perfonned by asuitable cutting tool on a machine which may be or resemble a lathe.After shearing, the coating 69 is then lapped to provide a perfectlysmooth surface of a thickness of the order of l mil. lf desired, adiamond shearing tool may be employed for shearing and truing themagnetic surface to be perfectly concentric and thereby eliminate theneed for the lapping operation.

Drum 62 is provided with an annular-shaped cavity 70 along its left-handsurface (relative to FIG. 5d) so as to form a substantially cylindricalportion 71 of reduced diameter relative to the outer diameter of drum62. Portion 71 is adapted to receive a cylindrical-shaped rotor member72 having an outwardly projecting flange 73 which is force-fitted uponportion 71 of drum 62.

A motor 73 is mounted within a hollow opening 74 provided in motormounting plate 53 and is secured thereto by suitable fastening means75,75. The leads 76 of motor 73 are provided for coupling to a suitableAC power source.

The stator 77 of motor 73 extends outwardly from the motor toward rotor72, and is provided for developing a moving flux field for rotation ofrotor 72. The motor employed herein is a drag cup motor. Energization ofthe stator sets up a magnetic field which slightly magnetizes amature(i.e. rotor) 72 which then drags around following the rotating flux eldgenerated by the stator. Since the rotor is force-fitted upon drum 62,both drum 62 and rotor 72 rotate in unison about shaft 60 when motor 73is energized. It should be noted that no mechanical coupling existsbetween the shaft 60 and motor 73. Concentricity of the motor stator 77and rotatable rotor 72, while not absolutely required, is obtainable byjudicious location of mounting plate 53 relative to baseplate 51.

Baseplate 51 is further provided with an aperture 78 for receivingelongated pin 79 which is force-f1tted into opening 78. A rigidelongated plate 80, which supports a magnetic head assembly to be morefully described, is provided with an opening 81 for receiving pin 79which pivotally mounts member 80 to baseplate 51. Member 80 is retainedupon pin 79 by means of a retainer clip 82 which substantially preventsany linear movement between pin 79 and member 80.

The right-hand end of member 80, relative to FIG. 5a, is provided withan opening 82 for receiving an elongated threaded member 83 having anouter diameter greater than the inner diameter 82 so as to be freelymovable within opening 82. Baseplate 51 is provided with an opening 84for threadedly engaging the end portion of threaded member 83 which isprovided with a head portion 83a for tightening the head mountingassembly for a purpose to be more fully described. The opening 82 inmember 80 may either be circular and of an inner diameter substantiallygreater than the outer diameter of threaded member 83, or may be oval inshape or an elongated slot so as to permit a certain degree of pivotalmovement in either of the directions shown by arrow 85 for the purposeof enabling adjustment of the airgap between the magnetic heads and thedrum magnetic surface.

Member is provided with a rectangular-shaped slot 86 for receiving amagnetic head assembly 87 which is clamped and thereby rigidly heldwithin slot 86 by means of a strap member 88 rigidly fastened to member80 by fastening means 89,89.

As shown best in FIG. Sb, the airgap G between magnetic head assembly 87and magnetic surface 69 is simply and accurately obtained by pivotingthe head assembly mounting member 80 about pin 79 until the appropriatesignal strength is obtained. As was previously described, the anglethrough which member 80 may rotate about pin 79 is controlled by theshape of the opening 82 of member 80, which opening is of aconfiguration sufficient to allow suitable movement of the magnetic headassembly relative to the cooperating magnetic surface 69 to assure aproper airgap setting. Alignment between the magnetic head assembly 87and the magnetic surface 69 is obtained by precisely positioning thelongitudinal axis of pin 79 and shaft 60 through precise location of theopenings 78 and 59 in baseplate 51 respectively receiving pin 79 andshaft 60. Threaded member 83 may be provided with a lockwasher 90 (seeFIG. 5c) to indefinitely retain the magnetic head assembly at the properairgap setting.

The openings 91 in baseplate 5l are employed to mount the memoryassembly upon a suitable supporting surface or framework through the useof fastening means and rubber grommets (not shown) to isolate vibration.

FIGS. 6a6d show still another preferred embodiment of the presentinvention in which the magnetic memory is mounted and effectively sealedwithin a housing to keep the unit dirt free and further to enable theunit to be utilized as a plugin assembly for applications in whichchanges in stored contents thereof may be made without performingerasure and write-in operations (i.e., for use, for example, as aread-only" memory). Obviously, the modular plug-in design may also beutilized as memory devices in systems requiring both read-in andread-out capabilities.

The embodiment of FIGS. 6a-6d is comprised of a first housing member 101having a hollow and relatively shallow interior 102 defined by the base101a and upwardly extending sidewalls I01d. FIG.- 7 shows a top planview which may be considered in conjunction with FIGS. 6a-6d for abetter understanding of this embodiment.

The base portion 101a of housing member 101 is provided with an opening103 surrounded by a raised surface area 104. The drum mounting assemblyof FIGS. 6a-6d is substantially identical to that shown in FIG. 5d, forexample, and therefore like numerals will be designated to identify likecomponents. As was previously described with respect to FIG. 5d, shaft60 is force-fitted into opening 103 and first supports a washer 6l anddrum 62 thereupon. Drum 62 is provided with a pair of jewel bearings,only one of which (bearing 64) is shown in FIG. 6b. A second washer 66and retainer ring 67 is then mounted upon shaft 60. Obviously, the otherdetailed features of the drum and its mounting assembly discussed withrespect to FIG. 5d may be and preferably are incorporated in the drumand mounting assembly of the embodiment of FIGS. 6a-6d.

The base portion 101a of housing member 101 is further provided with aslightly raised surface area 101b having openings 105 and 106. Opening105 receives a pin 106 (see FIG. 6c) force-fitted into the opening andpivotally supporting a magnetic head structure which is comprised of amagnetic head assembly 108 mounted within the central portion of asupporting structure 109 having outwardly extending arms l09a and 109bwhich are joined at their inward ends to the central portion 109e` andintegrally joined at their outer ends to hollow cylindrical members 110and 111 respectively. Pin 106 passes through the hollow opening ofcylindrical member 110 and is secured in this position by means of awasher 112 and retainer ring 113. The opposite cylindrical member 111receives a threaded fastener 112 which threadedly engages a tappedopening 113 in housing base portion I01a. The outer diameter of threadednumber 112 is substantially less than the inner diameter of the openingin cylindrical member 111 so as to permit a significant amount of playtherebetween for adjustment of the airgap in substantially the identicalmanner as was described with respect to the magnetic head assembly shownbest in FIGS. a and 5b. Thus, by adjusting the assembly for the preciseairgap desired and tightening the head 112a of threaded fastener 112,the desired airgap may be maintained indefinitely. Obviously, alockwasher may be provided between head 112a and the top surface ofcylindrical member 1 11. The central portion 109C may be provided with asuitable hollow opening for receiving and positioning the magnetic headassembly 108. The magnetic head assembly 108 may be permanently moldedwithin the support structure 109 or, alternatively, may be fitted withinthe opening and provided with a clamping bracket in much the same manneras that shown in FIG. 5a with the precise positioning of the clampingbracket being dependent only upon the needs of the user.

FIG. 7 shows the housing member 101 as being provided with a pluralityof bosses l 14a-1 14feach of which is provided with a tapped apertureor, alternatively, with an aperture capable of being tapped by means ofa self-tapping screw. Each of these bosses are in alignment withassociated openings (not shown) provided in a flat board 1 15 which ispreferably a board of the printed circuit variety in that it is formedof a suitable insulating material and has conductive areas such as, forexample, areas 116 for establishing electrical circuitry and/orconnections between and among various components of the memory system.The specific printed circuit configuration may assume any one of avariety of arrangements wherein packaging inner-electrode capacitancesand mechanical limitations are usually taken into account in suchprinted circuit layouts.

Printed circuit board 115 is positioned upon housing 101 as shown inFIGS. 6a6d, and receives a plurality of either threaded fasteners orself-tapping screws 117a-l17f which cooperate with the associatedopenings in the printed circuit board and the bosses 114a-l l4frespectively, to enable the printed circuit board to be rigidly fastenedto housing portion 101 and thereby provide a sealed housing for thecomponents of the memory which is substantially dirt free and is easy tohandle, remove, and/or replace from peripheral equipment for reasonswhich will be described more fully hereinbelow.

Printed circuit board 115 is further provided with an opening of asubstantially large diameter for receiving motor 118 which is secured toprinted circuit board 115 by fastening means 119a and 119b which extendthrough openings in flange 118a of motor 118. The opening in printedcircuit board 115 provides sufficient clearance for the projectiontherethrough of the stator assembly 118C, as shown best in FIG. 6b.

The motor 72 is force-fitted upon the drum member 62 in the same manneras was described with respect to FIG. 5d and, in operation, is slightlymagnetized upon energization of motor 118 and is then dragged around,following the rotating flux field set up by the motor stator 77.

The adjustment of the airgap between the magnetic head assembly 108 andthe drum surface is performed through the use of a separate assembly(not shown in the present application) which is comprised of a motorsimilar to motor 118 for rotating rotor 72 and drum 62. The leads (notshown) for the magnetic head assembly are coupled into test circuitryfor viewing purposes preferably by an oscilloscope, for example, thereadout signals while adjusting the airgap dimension. After suitableadjustment, screwhead 112a is tightened and the airgap adjustment isthereby fixed.

After the airgap adjustment is made, the leads of the magnetic headassembly are wired to appropriate conductive surfaces ofthe type shownby numeral 116. Likewise, the leads of motor 118 are wired toappropriate conductive surfaces of the printed circuit board so that allof the input power leads and output signal leads are available along theupper edge of printed circuit board 115 for connection to peripheralcircuitry which may be provided with an edge connector 120 shown at thetop of FIGS. 6a and 6d. The edge connector 120 may be permanentlyaffixed to the peripheral circuitry which utilizes a memory assembly ofthe type 100. The memory assembly is extremely advantageous for use insystems in which specific preprogrammed information may be insertedthrough the insertion of an assembly 100 containing recorded informationrequired for performing the desired program. Programs may be changed byremoving one such assembly and replacing it with another. Obviously, thesame advantages may be derived in cases where the memory assembly 100 isemployed as a memory which is capable of performing erasure andrewriting of data, as well as equipment utilizing assembly 100 as aready-only memory.

Although there has been described a preferred embodiment of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

l. A compact magnetic drum assembly comprising:

synchronous motor means for generating a revolving magnetic field;

a rotor assembly adapted to be rotatably driven by said synchronousmotor positioned in close proximity thereto;

a magnetic drum assembly comprising a cylindrical member open at one endthereof being firmly secured to said rotor assembly in a manner suchthat the rotor assembly in a portion of said rotor means lies within theinterior of said cylindrical drum;

housing means having a hollow interior for receiving said motor, rotorand drum assembly;

said synchronous motor means being secured to one face of said housing;

a magnetic head assembly;

retainer means secured to said housing for adjustably positioning themagnetic head assembly to said housing in order to provide apredetermined airgap between the surface of said magnetic drum assemblyand said magnetic head assembly;

said housing means being comprised of a first housing member and a coverplate;

said housing member being comprised of a substantially flat centralportion having first and second integrally formed sides dependingtherefrom;

the opposite edges of each of said sides being bent to form receivinggrooves for slidably receiving said cover plate;

said cover plate being comprised of a flat central portion having firstand second sides integrally fonned therewith and depending therefrom,the edges of said first and second sides being adapted to be slidablyreceived by the grooves provided along the marginal edges of the firstand second sides of said housing member.

2. The assembly of claim 1 wherein the flat central portion of saidhousing member is provided with first and second elongated slots and athird rectangular-shaped opening positioned between said first andsecond elongated slots;

a substantially C-shaped retainer clip having first and second sidesdepending from and integrally formed with a curved central portion;

said sides of said retainer clip extending through said first and secondelongated slots and having inwardly bent flanges at their distal endsfor embracing a magnetic head assembly to rigidly secure said magnetichead assembly to said housing member.

3. A magnetic drum assembly comprising:

a first mounting plate;

a shaft having a first end secured to said first plate;

a drum mounted to rotate about said shaft;

a second mounting plate secured to said first mounting plate arranged inspaced parallel fashion thereto with said drum being positioned betweensaid plates;

a motor having means for generating a revolving magnetic field in theregion between said plates;

an annular-shaped rotor secured to the face of said drum adjacent saidsecond plate;

said second plate having an opening;

said motor means being mounted to said second plate within said openingand in close proximity to said rotor for rotating the rotor and the drumabout said shaft;

a magnetic pattern being provided on the periphery of said drum;

a magnetic head assembly being adjustably secured to said first platefor enabling adjustment of the airgap between said drum periphery andthe magnetic head assembly;

the second end of said shaft being positioned a spaced distance awayfrom said motor means and said second plate to enable rotation of saiddrum and said rotor without the necessity of obtaining criticalalignment between said shaft and said motor.

4. The assembly of claim 3 wherein said second plate is a printedcircuit board having a plurality of conductive coatings for selectivelyelectrically connecting said motor means and magnetic head assemblythereto;

said printed circuit board having a first end extending beyondtheadjacent end of said first housing member;

said conductive surfaces extending to the first end of said printedcircuit board for facilitating releaseable connection to an edgeconnector assembly.

5. The assembly of claim 3 wherein said magnetic head assembly iscomprised of an arm having a first end pivotally mounted to said firstmounting plate and having an opening near the second end of said arm;

fastening means passing through said opening for securing said arm tosaid first mounting plate;

said opening being larger than the diameter of said fastening means forenabling adjustment of said airgap;

a magnetic head structure secured to said arm intermediate the endsthereof.

6. The assembly of claim 3 wherein said motor means is further comprisedof' stator means extending toward said drum and surrounding said rotor;

said drum being provided with an annular-shaped cavity surrounding saidrotor to provide adequate clearance for said stator means.

7. A magnetic drum assembly comprising:

a first housing member having a hollow interior and being open along onesurface thereof;

a shaft having a first end secured to the base of said housing member;

a substantially flat insulating member adapted to fit over the open faceof said housing member forming a hollow enclosure;

a drum mounted to rotate about said shaft and positioned within saidenclosure;

an annular-shaped rotor being secured to the face of said drum adjacentsaid insulating member;

said insulating member having an opening;

motor means having means for generating a revolving magnetic field;

said motor means being secured to said insulating member and positionedwithin said opening in close proximity to said rotor;

a magnetic pattern being provided on the periphery of said a magnetichead assembly being adjustably secured to said first housing memberwithin said enclosure for enabling adjustment of the airgap between saiddrum periphery and said magnetic head assembly.

8. The assembly of claim 7 wherein said magnetic head assembly iscomprised of an arm having a first end pivotally mounted to said housingmember and having an opening near the second end of said arm;

fastening means passing through said opening for securing said arm tosaid first housing member;

said opening being larger than the diameter of said fastening means forenabling adjustment of said airgap;

a magnetic head structure secured to said arm intermediate the endsthereof.

9. The assembly of claim 7 wherein said motor means is further comprisedof stator means extending toward said drum and surroundingsaid rotor'said drum being provided with an annular-shaped cavity surrounding saidrotor to provide adequate clearance for said stator means.

10. A magnetic drum memory including a hollow housing;

a cylindrical drum having a shaft supported by a first interior surfaceof said housing; said drum being rotatably mounted thereto;

the free end of said shaft extending toward a second interior surfaceparallel to said first interior surface;

a magnetic material being provided on the outer periphery of said drum;

said memory being characterized by providing a motor secured to saidsecond interior surface and positioned to one side of said drum;

said one side of said drum having a cylindrical-shaped recess facingtoward said motor;

said motor having a stator for generating a rotating magnetic field atleast partially extending into the region of said recess;

an annular-shaped rotor secured to said drum adjacent said recess andlying within the region of said rotating magnetic field for rotatingsaid rotor and said drum in unison;

the free end of said shaft being positioned a spaced distance from saidmotor and said second surface thereby avoiding the need for accuratelyand precisely centering said motor relative to said mounting means;

an adjustable magnetic head assembly for selectively writing or readinginformation in the magnetic material.

It Ik lll

1. A compact magnetic drum assembly comprising: synchronous motor meansfor generating a revolving magnetic field; a rotor assembly adapted tobe rotatably driven by said synchronous motor positioned in closeproximity thereto; a magnetic drum assembly comprising a cylindricalmember open at one end thereof being firmly secured to said rotorassembly in a manner such that the rotor assembly in a portion of saidrotor means lies within the interior of said cylindrical drum; housingmeans having a hollow interior for receiving said motor, rotor and drumassembly; said synchronous motor means being secured to one face of saidhousing; a magnetic head assembly; retainer means secured to saidhousing for adjustably positioning the magnetic head assembly to saidhousing in order to provide a predetermined airgap between the surfaceof said magnetic drum assembly and said magnetic head assembly; saidhousing means being comprised of a first housing member and a coverplate; said housing member being comprised of a substantially flatcentral portion having first and second integrally formed sidesdepending therefrom; the opposite edges of each of said sides being bentto form receiving grooves for slidably receiving said cover plate; saidcover plate being comprised of a flat central portion having first andsecond sides integrally formed therewith and depending therefrom, theedges of said first and second sides being adapted to be slidablyreceived by the grooves provided along the marginal edges of the firstand second sides of said housing member.
 2. The assembly of claim 1wherein the flat central portion of said housing member is provided withfirst and second elongated slots and a third rectangular-shaped openingpositioned between said first and second elongated slots; asubstantially C-shaped retainer clip having first and second sidesdepending from and integrally formed with a curved central portion; saidsides of said retainer clip extending through said first and secondelongated slots and having inwardly bent flanges at their distal endsfor embracing a magnetic head assembly to rigidly secure said magnetichead assembly to said housing member.
 3. A magnetic drum assemblycomprising: a first mounting plate; a shaft having a first end securedto said first plate; a drum mounted to rotate about said shaft; a secondmounting plate secured to said first mounting plate arranged in spacedparallel fashion thereto with said drum being positioned between saidplates; a motor having means for generating a revolving magnetic fieldin the region between said plates; an annular-shaped rotor secured tothe face of said drum adjacent said second plate; said second platehaving an opening; said motor means being mounted to said second platewithin said opening and in close proximity to said rotor for rotatingthe rotor and the drum about said shaft; a magnetic pattern beingprovided on the periphery of said drum; a magnetic head assembly beingadjustably secured to said first plate for enabling adjustment of theairgap between said drum periphery and the magnetic head assembly; thesecond end of said shaft being positioned a spaced distance away fromsaid motor means and said second plate to enable rotation of said drumand said rotor without the necessity of obtaining critical alignmentbetween said shaft and said Motor.
 4. The assembly of claim 3 whereinsaid second plate is a printed circuit board having a plurality ofconductive coatings for selectively electrically connecting said motormeans and magnetic head assembly thereto; said printed circuit boardhaving a first end extending beyond the adjacent end of said firsthousing member; said conductive surfaces extending to the first end ofsaid printed circuit board for facilitating releaseable connection to anedge connector assembly.
 5. The assembly of claim 3 wherein saidmagnetic head assembly is comprised of an arm having a first endpivotally mounted to said first mounting plate and having an openingnear the second end of said arm; fastening means passing through saidopening for securing said arm to said first mounting plate; said openingbeing larger than the diameter of said fastening means for enablingadjustment of said airgap; a magnetic head structure secured to said armintermediate the ends thereof.
 6. The assembly of claim 3 wherein saidmotor means is further comprised of stator means extending toward saiddrum and surrounding said rotor; said drum being provided with anannular-shaped cavity surrounding said rotor to provide adequateclearance for said stator means.
 7. A magnetic drum assembly comprising:a first housing member having a hollow interior and being open along onesurface thereof; a shaft having a first end secured to the base of saidhousing member; a substantially flat insulating member adapted to fitover the open face of said housing member forming a hollow enclosure; adrum mounted to rotate about said shaft and positioned within saidenclosure; an annular-shaped rotor being secured to the face of saiddrum adjacent said insulating member; said insulating member having anopening; motor means having means for generating a revolving magneticfield; said motor means being secured to said insulating member andpositioned within said opening in close proximity to said rotor; amagnetic pattern being provided on the periphery of said drum; amagnetic head assembly being adjustably secured to said first housingmember within said enclosure for enabling adjustment of the airgapbetween said drum periphery and said magnetic head assembly.
 8. Theassembly of claim 7 wherein said magnetic head assembly is comprised ofan arm having a first end pivotally mounted to said housing member andhaving an opening near the second end of said arm; fastening meanspassing through said opening for securing said arm to said first housingmember; said opening being larger than the diameter of said fasteningmeans for enabling adjustment of said airgap; a magnetic head structuresecured to said arm intermediate the ends thereof.
 9. The assembly ofclaim 7 wherein said motor means is further comprised of stator meansextending toward said drum and surrounding said rotor; said drum beingprovided with an annular-shaped cavity surrounding said rotor to provideadequate clearance for said stator means.
 10. A magnetic drum memoryincluding a hollow housing; a cylindrical drum having a shaft supportedby a first interior surface of said housing; said drum being rotatablymounted thereto; the free end of said shaft extending toward a secondinterior surface parallel to said first interior surface; a magneticmaterial being provided on the outer periphery of said drum; said memorybeing characterized by providing a motor secured to said second interiorsurface and positioned to one side of said drum; said one side of saiddrum having a cylindrical-shaped recess facing toward said motor; saidmotor having a stator for generating a rotating magnetic field at leastpartially extending into the region of said recess; an annular-shapedrotor secured to said drum adjacent said recess and lying within theregion of said rotating magnetic field for rotating said rotor and saIddrum in unison; the free end of said shaft being positioned a spaceddistance from said motor and said second surface thereby avoiding theneed for accurately and precisely centering said motor relative to saidmounting means; an adjustable magnetic head assembly for selectivelywriting or reading information in the magnetic material.